Capillariasis FAQs

What is capillariasis?

Capillariasis is a parasitic infection cause by two species of nematodes, Capillaria hepatica, which causes hepatic capillariasis, and Capillaria philippinensis, which causes intestinal capillariasis. There are medications and treatment options available to cure both forms of capillariasis, but, without treatment, capillariasis can lead to death.

How does one become infected?

C. hepatica is often found in the liver of animals such as small rodents, monkeys, and prairie dogs and can cause cirrhosis in these animal hosts. When these animals are eaten by larger carnivores, capillarid eggs are ingested and passed through the fecal matter of the carnivore. When this fecal matter is deposited in the soil, these eggs become infective in about 30 days and can infect other animals, including humans. Once accidentally ingested by a human, the eggs migrate to the liver and mature to adult worms. Another route of transmission is through the decomposition of infected animals via eggs in the liver being released into the soil.

C. philippinensis is often found in the tissues of small, freshwater fish. When humans ingest these raw or undercooked infected fish, larvae migrate to the intestine and mature to adult worms. Female worms deposit eggs in the intestine, which are released in fecal matter. When infected human fecal matter reaches freshwater, fish can become infected and the cycle continues. Some eggs hatch within the human intestine causing hyperinfection (a massive number of adult worms).

Where is it found?

Infection with C. hepatica is rare but has been reported worldwide. Infection with C. philippinensis is frequently found in the Philippines and Thailand. Some cases have been found in other Asian countries, the Middle East, and Colombia.

How is it diagnosed?

C. hepatica can be diagnosed by performing a liver biopsy, needle biopsy, or after death at autopsy. Analyzing stool samples for C. hepatica cannot be used to diagnose infection. C. philippinensis can be diagnosed by taking a biopsy of the tissue of the small intestine or by analyzing stool samples.

Can this be transmitted human to human?

C. hepatica can be transmitted human to human when eggs are deposited through human fecal matter into the soil. The eggs then become infective in the soil, and humans ingest infective soil directly by eating soil (pica) or indirectly through contaminated food or water.

C. philippinensis cannot be transmitted human to human and requires the intermediate freshwater fish host. However, adult C. philippinensis worms in humans can release eggs that hatch into larvae in the intestine and cause hyperinfection.

What are the signs and symptoms?

When a human is infected with only one C. hepatica worm, there are often no signs or symptoms. With multiple worms and female worms that lay eggs continually, the clinical manifestations of C. hepatica include hepatitis, anemia, fever, hypereosinophilia, and even death.

When a human is first infected with C. philippinensis, the signs and symptoms include general abdominal pain and diarrhea. Later on, nausea, vomiting, weight loss, and even death can occur.